JPH0424340B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is based on the general formula () [In the formula, X represents a chlorine atom or a bromine atom. ]
This relates to a carbonate ester represented by The compound of the present invention represented by the general formula () is useful as a synthetic intermediate for the compound represented by the following general formula () having herbicidal activity. [In the formula, R represents an alkyl group, an alkenyl group, or an alkynyl group, and X represents the same meaning as above. ] The compound represented by the general formula () has little phytotoxicity against important effects on corn, wheat, rice, soybean, soybean, etc., and has strong herbicidal power against weeds, and is a typical As a compound, for example, 2-(4-chloro-2-fluoro-
5-isopropoxyphenyl)-3,4,5,6
-tetrahydrophthalimide (compound 1 in Table 1), 2-(4-chloro-2-fluoro-5-propargyloxyphenyl)-3,4,5,6-tetrahydrophthalimide (compound 2 in Table 1),
There is 2-(4-chloro-2-fluoro-5-allyloxyphenyl)-3,4,5,6-tetrahydrophthalimide (compound 3 in Table 1), and their herbicidal activity is as described below. .

[Table] In the following test examples (reference examples) for herbicides, evaluations of phytotoxicity to cultivated plants and efficacy against weeds were all based on the criteria described below.
It is expressed as an evaluation value using an integer from to 5. The fresh weight of the above-ground parts of the plants that remained withered at the time of the survey was measured, and the ratio (%) compared to the fresh weight of the plants in the untreated area was calculated. Cultivated plants and weeds were evaluated for chemical damage and herbicidal efficacy using numbers from 0 to 5 based on the criteria shown in the table below. An evaluation value of 0 or 1 for cultivated plants or an evaluation value of 5 or 4 for weeds is generally considered to be an appropriate cultivated plant protection effect or weed control effect.

【table】

[Table] Reference example: Corn weed control test (stem and foliage treatment) A plastic tray measuring 35 cm long, 25 cm wide, and 10 cm high was filled with field soil, and corn, Japanese radish, sunflower, Ebisugusa, Maruba morning glory, Wildflower, chickweed, and Japanese foxtail were sown. After growing in a greenhouse for two weeks, two of these trays were lined up in a frame measuring 50cm long, 100cm wide, and 40cm high, and a small sprayer was used from above the plant to apply a prescribed amount of each chemical to the entire area within the frame. . After being grown at room temperature for an additional three weeks after spraying, each plant was examined for chemical damage or herbicidal efficacy. The results are shown in Table 2. The processing agent used was an emulsion, which was emulsified in water to which a spreading agent was added. The size of the plants at the time of chemical treatment varied depending on the species, but they were approximately 2 to 20 cm tall at the 1 to 3 true leaf stage.

【table】

[Table] A compound useful as a herbicide represented by the general formula () can be synthesized from the compound of the present invention represented by the general formula () by the following reaction route. [In the formula, X and R are as described above.] ] In other words, the phenol derivative of the general formula () can be prepared using an alkali metal carbonate such as potassium carbonate, an alkali metal hydroxide such as potassium hydroxide, or an alkali metal hydrogen such as sodium hydride in a solvent such as dimethylformamide or dimethyl sulfoxide. 0 to 100 with an alkyl halide, alkenyl halide, or alkynyl halide in the presence of an alkali metal alkoxide such as a compound, sodium alkoxide, etc., preferably in the presence of an alkali metal carbonate.
It is converted into an N-phenyltetrahydrophthalimide derivative of the general formula () by reacting at a temperature of 70 to 90°C. The phenol derivative of general formula () is the aminophenol derivative of general formula () and 3,4,5,
It can be produced by refluxing 6-tetrahydrophthalic anhydride in an inert solvent such as acetic acid for 1 to 6 hours, generally 2 to 4 hours. The aminophenol derivative of general formula () can be obtained by reducing the nitrophenol derivative of general formula (). Any of the common methods for reducing the nitro group on the aromatic ring, such as catalytic reduction, reduction using iron powder, reduction with sodium sulfate, and reduction with sulfurized NaBH ₄ , is possible, but platinum dioxide as a catalyst Reduction with hydrogen in an ethanol solvent at room temperature and pressure is preferred. The aminophenol derivative of the general formula () obtained by this catalytic reduction can be used for reaction with 3,4,5,6-tetrahydrophthalic anhydride almost without purification. The nitrophenol derivative of the general formula () can be prepared by adding the compound of the present invention of the general formula () using an alkaline aqueous solution such as sodium hydroxide, preferably at 40 to 80°C.
It can be obtained by hydrolysis with The compound of the present invention of the general formula () is a compound of the general formula ()
It can be produced from halophenol according to the following reaction formula. [In the formula, X is as described above. ] Halofenol of general formula () is GC
Finger et al., J. Am. Chem. Soc. 81 94 (1959). Halofenol of the general formula () is made into an alkali metal salt with an aqueous solution such as sodium hydroxide or potassium hydroxide, and then reacted with methyl chloroformate in an aqueous solution, preferably at 0 to 10°C, to form a carbonate of the general formula (). Ester derivatives can be obtained. Further, by carrying out nitration using agricultural sulfuric acid and concentrated nitric acid at room temperature, the compound of the present invention represented by the general formula () can be produced. Example 1 Synthesis of methyl 2-chloro-4-fluoro-5-nitrophenyl carbonate 83.4 g of 2-chloro-4-fluorophenol was added to an aqueous sodium hydroxide solution prepared from 27.7 g of sodium hydroxide and 450 ml of water. 69.2 g of methyl chloroformate was added dropwise at below 10°C. The resulting crystals were separated and washed with water to obtain 134.8 g of crude methyl 2-chloro-4-fluorophenyl carbonate. mp69~71℃ Methyl 2-chloro-4-fluorophenyl carbonate 134.8 was suspended in 50ml of concentrated sulfuric acid, mixed acid (50ml of concentrated sulfuric acid, 50ml of concentrated nitric acid) was added dropwise at around 30℃, and the temperature was maintained for another hour. It was stirred with The reaction solution was poured into ice, and the crystals formed were washed repeatedly with water and 143
g of methyl 2-chloro-4-fluoro-5-nitrophenyl carbonate was obtained. mp58-55℃ Example 2 Synthesis of methyl 2-bromo-4-fluoro-5-nitrophenyl carbonate 28 g of 2-bromo-4-fluorophenol was dissolved in an aqueous sodium hydroxide solution (7 g of sodium hydroxide
(dissolved in 100 ml of water), methyl chloroformate was added dropwise at below 10°C, and the resulting crystals were separated and washed with water to obtain 41 g of methyl 2-bromo-4-fluorophenyl carbonate. mp80.7℃ Suspend this in 13ml of concentrated sulfuric acid, add 13ml of concentrated sulfuric acid,
A mixed acid containing 13 ml of concentrated nitric acid was added dropwise at around 30°C. moreover
Stir for 30 minutes, pour into ice, wash the formed crystals well with water, and obtain methyl 2-bromo- as 38.3 g of yellow crystals.
4-Fluoro-5-nitrophenyl carbonate was obtained. mp63.5~64.5℃.

Claims (1)

[Claims] 1. General formula [In the formula, X represents a chlorine atom or a bromine atom. ]
Carbonic ester represented by.